The effect of nitrogen intake, sulphur intake and dietary nitrogen source on the performance of the early weaned calf

Abstract

An experiment was conducted with 40 male Friesian calves between five and eleven weeks of age to estimate their nitrogen and sulphur requirement. The basal diet contained 2.2 per cent nitrogen which was supplemented with urea or meat meal to 3.1 per cent nitrogen. The urea was added both with and without sodium sulphate. The weight gain and efficiency of feed conversion ratio of the calves fed the diet containing 2.2 per cent nitrogen was lower than that of the calves fed the diets containing 3.1 per cent nitrogen, but they were not affected by the nature of the nitrogen supplement or by the addition of sulphur to the urea supplemented diet which already contained 0.11 per cent sulphur. The apparent digestion of organic matter, dry matter, and nitrogen was greater at six weeks of age than at ten weeks of age. The excretion of nitrogen in the urine was greater in the calves fed the diets containing urea, but there was no difference in nitrogen retention. The retention of sulphur was 0.47 g a day for the calves fed the diet containing 0.11 per cent sulphur compared with 0.85 to 1.75 g a day for the calves fed the other diets. The concentration of urea in the blood plasma was higher in the calves at five weeks of age than at ten weeks of age and increased with increased nitrogen intake. The concentration of urea in the blood plasma was higher in the calves whose diet included urea than in the calves fed the meat meal supplemented diet.